Can't login as diku_admin after logging in and out as other user.

Platform: http://folio-testing.aws.indexdata.com/

Path to problem:
1) Create a new user or use an existing one (username usually equals password)
2) Login as the new user.
3) Logout new user
4) Try to login as diku_admin (or any other user, actually)

Error: Nothing happens-- there is no response from server after clicking login button.

Note: You can login as diku_admin if you do a hard refresh of the login page (command-shift-R on Mac.)